Siberian nematode worms revived after being frozen for 42,000 years

Low-temperature
scanning electron micrograph of soybean cyst nematode and its
egg. Magnified 1,000 times.
Agricultural Research Service/ Wikimedia
Commons

• Russian scientists have revived tiny worms that had
  been frozen for 42,000 years.
• After being removed from Siberian permafrost, the worms
  were gradually thawed in a lab until they started moving around
  and consuming food.
• The scientists say their findings could have
  implications for astrobiology and cryomedicine. 

A group of Russian scientists have successfully revived two
species of tiny worms that they discovered suspended in an icy
chunk of Siberian permafrost.

The worms, known as nematodes or more commonly as roundworms, had
been frozen for up to 42,000 years, since a time when much of the
planet was covered in ice.

But they weren’t dead — just cyrogenically preserved. 

The researchers brought the worms back to a lab, where they
slowly thawed them over several weeks. The researchers put them
in petri dishes with food, stored at 
20 degrees
Celsius (68 degrees Fahrenheit).

As they warmed, the worms started showing signs of
life, moving and eating. That marks the first
documented time multi-cellular organisms have returned to
functioning after being frozen in permafrost. 

The researchers published their findings in the journal Doklady
Biological Sciences in May, and the study became
available online this month. In the report, the authors
acknowledge that certain types of bacteria, algae, yeasts, seeds,
and spores have been found to remain viable even after being
frozen in permafrost for thousands or even millions of years. But
an organism as complex as the nematode has never been shown to be
capable of this.

Until now, the longest nematodes had been dormant then
revived was 39 years,
according to Science Alert. Similarly,
tardigrades that had been frozen for 30 years were
brought back to life by Japanese researchers in 2016,

as Gizmodo pointed out. 

The permafrost samples came from the remote Yakutia
region in Siberia. The researchers analyzed over 300 samples, and
selected two that had well-preserved nematodes in them. One of
the samples was 100 feet deep and estimated to have frozen 32,000
years ago, while the other was just over 11 feet deep and froze
42,000 years ago. 

The scientists said they can’t rule out the possibility that the
samples were contaminated at some more recent point, but said
they kept the experiment as sterile as possible. So the most
likely explanation is that the worms were indeed revived after
being frozen for millennia. 

Nematodes are impressive little worms, though they measure
less than 1 millimeter across. They’ve been found living
almost a mile below the Earth’s surface, and some have even
adapted to living inside slug intestines,
according to Live Science. 

The Russian team noted in the paper that their findings
could have implications for astrobiology — the search for life
outside our planet — as well as cryomedicine and cryobiology,
which is the study of how extremely low temperatures affect
life.